Process of reducing hematite to magnetic iron oxid.



"UNTTE TATE TATENT Olfili llfil l,

STEN LIIJA, OF BAYONNE, NEW JERSEY, ASSIGNOR OF ONE-THIRD TO J. W.I-IUGO HAMILTON, OF ST. GEORGE, STATEN ISLAND, NEW YORK, AND ONE-THIRDTO NILS V. HANSELL, 0F CALDWELL, NEW JERSEY.

PROCESS OF REDUCING HEMATITE TO MAGNETIC IRON OXID.

censee.

N0 Drawing.

Specification of Letters Patent.

Application filed October 25, 1910.

Patented Aug. 22, 1911.

Serial No. 589,051.

T 0 all whom, it may concern:

Be it known that I, STEN LTLJA, a subject of the King 031 Sweden, andresiding in Bayonne, in the county of Union and State of New Jersey,have invented a certain new and Improved Process of Reducing Hematite toM a gnetic lron Oxid, of which the following is a specification.

My invention has as its principal object a process Off obtainingmagnetic iron oxid, c. g. magnetite (Fell), from a mixture of hematite(Fe,O,,) and a natural sulfur compound of iron and particularly to aprocess in which this is accomplished by mixing with the hematite asuitable quantity of pyrrhotite (F08) or pyrites (FeSQ both of whichoccur in large quantities in certain sections of the hemisphere, andcausing a reaction between the same whereby magnetic iron oxid isproduced which may be readily concentrated magnetically and briqueted ornodulized for use in the blast or open hearth furnace.

\Vhile as stated, I contemplate princi 'mlly the use of the naturalsulfur compound of iron mentioned, the desired reaction may be obtainedby mixing the hematite with sulfur or subjecting the same to the actionof sulfurous acid gas under suitable conditions.

Up to the present time the magnetic separation of close grained lowgrade hematites has been accompanied by practically insurmountableditliculties by reason of the slight difference in permeability betweenthe iron mineral and the gangue minerals of the ore. It has beenproposed to reduce the hematite by heating it with a small amount ofcarbon, and experimentally this has been successfully accomplished, butpractically it has not met with success for various reasons.

The present invention contemplates primarily the addition. to a quantityof hematite (Fe,0,,), of a suitable proportion of a natural sulfurcompound of iron, such as pyrites (FeS,) or pyrrhotite (Fe/S), and thenheating the mixture in finely ground condition to a temperature suitablefor the desired reaction. It is preferable to first crush the ores andafter determining the proper proportions then grind them together, sinceby this method a very intimate mixture is secured which is favorable tothe reaction. The proportions of the mixture vary with the naturalsulfur compound of iron which is employed and the richness of the crudeores. l urthermore the necessary proportions vary with the amount ofoxygen admitted during the reaction. The term peraturcs at which thereaction may be obtained are various, but l have discovered that it maybe successfully carried out at as low a temperature as 500 C.

The following equations illustrate the reaction. Usingpyrites (FeS. asthe natural sulfur compound, the reactions in a closed chamber are,principally, as follows 2-- n 1ea e ents;ur o cso lf the reaction becarried on in the presence of a greater or less quantity of oxygen thereactions will vary as illustrated in the following equations litpyrrhotitc (FcS) be used as the natural sultur compound the chiefreactions in a closed chamber arez while with oxygen present thereactions are:-

Several of the roasting kilns now in genoral use may be employed forcarrying out the process, for instance the rotary kilns partially closedat both ends through which the ore is slowly passed during the roasting.A modified type of the mechanically operated pyrites burner may also beemployed.

The resulting product may contain an appreciable amount of sulfur. Thishowever is no detriment inasmuch as being finely ground it must benodulized or briqueted-before being introduced into the iron furnaces,and the sulfur will be expelled in the nodulizing or briqueting furnace.

Various other modifications of the process will readily suggestthemselves, and I do not limit myself to the example given.

I claim as my invention 2 1. The process of reducing non-magnetic ironoxid to magnetic iron oXid which consists in mixing therewith a suitableproportion of a natural sulfur compound of iron and bringing the mixturein finely divided condition to reaction temperature, substantially asdescribed.

2. The process of obtaining magnetic iron oXid which consists in heatingto reaction temperature a finely divided mixture of hermatite and asulfur compound of iron OXlCl as pyrites or pyrrhotite, whereby saidiron compounds are reduced to magnetic oXid of iron, substantially asdescribed.

3. The process of obtaining magnetic iron OXlCl which consists ingrinding together 30 suitable proportions of hematite and a naturalsulfur compound of iron such as pyrites or pyrrhotite, and bringing themixture to reaction temperature, substantially as described.

4:. The process of reducing low grade iron oXid to magnetic iron oXidwhich consists in combining sulfur with a portion of its oxygen contentat an elevated temperature whereby said portion is eliminated in the 40form of a gas and the ore reduced to magnetic oxid of iron,substantially as described.

5. The process of reducing non-magnetic iron oxid to magnetic iron oXidwhich consists in causing a predetermined proportion 45 of a naturalsulfur compound of iron to react therewith in finely divided condition,substantially as described.

In testimony whereof I have signed my name to this specification, in thepresence of 50 two subscribing witnesses.

STEN LILJA.

Witnesses:

N. V. HANSELL, WM. I. BATEMAN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

Washington, D. C.

